Engine and gas generator

ABSTRACT

A two-cycle piston-cylinder combination which acts as an engine to provide shaft power or, alternatively, as a gas generator to provide turbine power. There are valve devices for maintaining hot gases out of contact with lubricants, means for actuating such valve devices, and means for combusting fuel in such cylinder.

Elite States Foster aten 1 1 1 1 Jan. 23, 1973' 1541 ENGINE AND GAS GENERATOR [761 Inventor:

Avenue, Redondo Beach, Calif [22] Filed: Sept. 8, 1970 [21] Appl. No.: 70,387

[52] 11.8. Cl. .123/47 R, 123/47 AB, 123/51 B, 123/56 B, 123/65 R [51] Int. Cl ..F02l 11/00 [58] Field ofSearch-..... ...60/l3 F, 15 FP; 123/46 R. 123/46 A.46 B,47 R,47 B,47 C.32.51R.

[56] References Cited U NlTED STATES PATENTS 1,785,643 Noack et a1 1f. ..60/15 FP Berry W. Foster, 2415 Thomas 2,408,030 9/1946 BLME 123/51 8 2.599908 6/1952 GChflllldl 123/32 2,611,349 9/1952 Parrish 1 ..123/51 is 3,112,607 12/1963 Addie 60/131 3,143,850 8/1964 Foster... ..60/l5 3,151,602 10/1964 Phillips 123 47 Primary ExaminerLaurence M Goodridge -All0rne v-Owen, Wickersham 8L Erickson [57] ABSTRACT A tw'o c y le jSis iEn cyliiitier 'c oiiiliinatinwlififi acts as an engine to provide shaft power or. alternatively, as a gas generator to provide turbine power. There are valve devices for maintaining hot gases out of contact with lubricants. means for actuating such valve devices, and means for combusting fuel in such cylinder.

29 Claims, 21 Drawing Figures PATEHTEDJM 31m SLEET 5 BF 3 FIG. 8-

I INVENTOR BERRY W FOSTER Hwy/M PATENTEnJmzsli-m 31122-76 sum 70; 3

' INVENT OR BERRY vv. FOSTER AT TORNE'YS PATEHTEDmzsm 3,712,276

' SHEET 80F a INVENTOR. BERRY W, FQS TER 1 ENGINE AND GAs GENERATOR SUMMARY OF THE INVENTION This invention relates to improvements in a twocycle piston-cylinder combination which can act as an engine to provide shaft power or as a gas generator to provide turbine power, or which can be useful for other purposes.

Thus, one object of this invention is to eliminate the need for sleeve ports to scavenge a two-cycle engine. This novel scavenging means may be used in a single piston with a cylinder head; it can also be used in opposed-piston arrangements. For a single piston, my new engine may be scavenged and charged. through the piston head by employing a valve arrangement similar to the one shown by FIGS. 7-13 of my US. Pat. No. 3,340,854. The improvement over that patent is an exhaust channel which may be provided inside the piston cylinder to eliminate the need for sleeve ports; thus, the piston can be lubricated and its seal rings hold the oil consumption to as low a rate as is achieved by the best four-cycle engine. Another arrangement of the single piston engine may use a combination of the camoperated poppet-valves in the cylinder head and the inertia-o'perated valves in the piston head with exhaust channels inside the piston to provide larger intake and exhaust port areas than most four-cycle engines have.

The opposed piston arrangement may be provided with an intake valve in one piston and an-exhaust valve in the opposite piston with an exhaust'channel inside this piston. This opposed-piston arrangement will have unidirection scavenging with no oil-consuming sleeve ports.

Another feature of this invention is an improvement on the inertia-operated valve shown in my U.S..Pat. No. 3,340,854, to provide means for locking the valve closed until it approaches its crank end. For an engine with large pistons and long strokes, the inertia-operated valve is the preferred-design. When the engine pistons are small and their strokes short, a valve located in the piston with a cam opening device in the engine housing is the preferred design.

The two-cycle engine of this invention may be used to produce shaft power directly by means of a piston driven mechanism, or it may be used to generate compressed air and .hot exhaust gases which may be'expanded through a gas turbine to produce shaft power.

This engine or gas generator is unique in that it may employ a semi-free piston. The piston may be free to adjust the stroke for the compression ratio at the engine head endfor compression ignition; however, at the crank end of its stroke, the piston may be limited by a toggle action of its oscillating crank action. The volumetric efficiency of the compressor for this semi-free compressed gas generator will be higher than the corresponding value obtained in the conventional freepiston engine. I

This oscillating crank or toggle mechanism makes it possible to employ a rotating or an oscillating flywheel instead of a recoil piston to drive the engine piston to compression ignition pressures. The flywheel may be geared to rotate or oscillate at several times the frequency of the oscillating pistons, thus it will bemore' effective for a given mass inertia. The semi-free piston will have a wider operating speed range. than afreepiston engine with a recoil piston.

In the current crank-and-rod engines there is considerable side'load on the piston and cylinder walls when the high-pressure gases act on the piston during its expansion stroke. This invention uses a novel ar- 5 rangement of two counter-rotating cranks and rods on each piston in an opposed-pistonengine to eliminate practically all of this high side load from the piston and cylinder; thus the piston will have less drag and wear. The connecting rods and cranks are phased so that the A side load is equally distributed between them and goes directly into the connecting rod and crank bearings. This unique means of eliminating side loads from pistons may also be used in my semi-free piston engine. In the semi-free piston engine with counter-oscillating levers and in the crank-and-rod engine with two counter rotating cranks and rods on each piston, the resultant force on the rods is designed to go through the center line of the piston cylinder.

This invention describes an opposed-piston engine which is dynamically balanced,and it'has little or no side loads on the piston due to pressure forces. A standard building block concept may be used to increase the power output and give more uniform torque for larger engines. For example, a standard opposed piston engine block of this invention can produce 100 horsepower. Two such engines can be coupled together and phased l80apart to produce 200 horsepower. Three opposed-piston engines can be coupled together and phased 120 apartto produce 300 horsepower, etc. This invention also relates to improvements in piston gas generators.

One of the weaknesses of the free-piston gas generator is thatithas to generate the full charge of compressed gas for each stroke, even at slow idling speeds when this charge is not needed. Also the frequency range of the free-piston engine is very narrow, and it cannot operate at slow speeds as can a diesel or an Otto engine. The gas generator of this invention as well as mypiston gas generator of.U.S. Pat. No. 3,143,850 can be converted to simple diesel engines which idle at slow speeds and do not have to generate any high-pressure gases or low-pressure gases. My I two types of gas generators, which may be converted to simple diesel engines, are more efficient than a free-piston gas generator especially for interrupted and variable speed mobile power applications such as trucks, buses, au-

tomobiles, tractors, trains, etc.

This invention also features an engine which has better thermal'and combustion efficiencies than the presentdiesel and Otto engines. Also, because of the charging through the pistons, there will not be any blow-bygases in the engine crankcases. Thus the en- 55 gine of this invention generates considerably less smog than the present diesel and Otto engines. After-burning can be provided if desired, in the low pressure piston motor to insure complete combustion. This after burning will heat gasesthat are expanded to do useful work.

BRIEF DESCRIPTION OF DRAWINGS In the drawings:

FIG. 1- is a sectional horizontal view of an opposedpiston two-cycle engine according to this invention having a common cylinder, two pistons therein, inlet means in one piston head and exhaust means in the other piston head, and means for sealing the piston so that the flow of oil into the engine cylinder is restricted to a minimum.

FIG. 2 is a schematic plan view of the crank-and-rod opposed-piston engine with a turbo-charger, taken on line 2-2 of FIG. 3, with both sides of the cylinder shown to include all the synchronizing gears and four crank-and-rod mechanisms to keep the large side loads off the pistons and maintain the engine in dynamic balance.

FIG. 3 is a sectional view taken on line 33 of FIG. 2, showing the piston drive means and other features.

FIG. 4 is a cross-sectional view of an opposed-piston engine including cooling systems to employ a cooling gas and a cooling liquid to reduce the temperatures of the engine exhaust gases and to prevent cracking or over-heating of the lubricating oil, and also showing an arrangement of valve-control means, with exhaust and intake valves fully open-and the pistons being near the maximum outward position, giving full expansion of the engine gases.

FIG. 5 is a view in cross-section of a portion of the device of FIG. 4, showing the valve'control arrangements for opening and closing the intake valve in the piston head, where the pistons are near their mid-inward stroke and the central cam on the engine structure is about to unlatch the toggle latches, so that the pneumatic springs will accelerate closure of the intake and exhaust valves.

FIG. 6 is another view of the portion of the device shown in FIG. 5 but wherein the intake value is in closed position and seated against its port, as the pistons move inward from their midstroke, whereby a charge of air is trapped and compressed in the engine cylinder.

FIG. 7 is still another view of the device of FIGS. 5

and 6 but wherein, while the intake valve is still seated, v

the forces on the large or inertial control mass acts towards the piston head end and moves it in that direction that the snap latches will hold it in its inward piston position. The engine pistons are near their closest together position where fuel is exploded in the engine cylinder.

FIG. 8 is a further view of the device wherein the hot gases in the engine cylinder have expanded and forced the pistons apart to near their outward stroke, and the upper cam is about to tripthe extended toggle so that the inertia forces on the large mass will open the valves.

FIG. 9 is' a view taken on line 9-9 of FIG. 8 and showing particularly the three parallel toggle links within the valve-control piston; the center toggle moves counter to the two outside toggles, thus the dynamic loads of the links as they move are in dynamic balance and do not cause any unbalance loads on the piston.

FIG. 10 is a fragmentary section view of an opposedpiston engine with poppet valves in the piston heads.

The valves are opened by a cam which is located in the engine cylinder housing. The pistons are approaching their most, outward position at their crank end. The cam has turned to contact the valve stem and start opening the valve.

FIG. ll is a fragmentary section view similar. to FIG. 10. The pistons have moved a short distance from their most outward position at their crank end, and the cam has turned to open the valves so thatthe hot expanded gases cam be discharged and a fresh charge of supercharged air will scavenge and supercharge theengine.

FIG. 12 is a fragmentary section view similar to FIGS. wand 11. The pistons have movedinward'to near their mid-stroke position. The. cams have turhed to lift the valves so that they will seat in their respective ports near the mid-inward stroke.

FIG. I3 is a fragmentary section view similar to has. 10 to 12. The pistons have moved together to compress the air which is trapped in the engine cylinder; the valves have moved away from the cam, and the cams continue to turn freely. The cam turns at a rotating speed which is twice the frequency of the pistons; thus the cam rotates 360 without contacting the valve-lifting means as the pistons move past their mid-inward stroke to their closest-together position and outward past their mid-outward stroke.

FIG. 14 is a fragmentary section view similar to FIGS. l0.to 13. The hot gases expand and do work on the pistons and forcethem apart as the valves remain closed. The cams continue to turn and contact the valve opening means a short distance before the pistons are near their furthest-apart position at their crank end as shown by FIG. 10.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 illustrates an opposed-piston two-cycle engine 38 according to this invention and shows the protected flow of gases thereth rough, the engine 38 comprising a housing 39, a common cylinder 11 and pistons 40 and 40'. In each head, 41" of the pistons is centrally disposed a port 42, 42' into which a valve head 43, 43 seats, respectively. Disposed adjacent the cylinder 11 is a gear train comprising gears 44, 45, 46 and 47, of whichthe the gear 44 is affixed to a shaft 53 which bears on the cylinder 11, the other endof the shaft 53 bearing a rocker arm 48; and the gear 47 is affixed to a shaft 53' which bears on the cylinder 1. The other end of the shaft 53' is affixed to a rocker the arm 48. Pivotally connected to arm 48 are rods 49 and 49; and to the arm 48', rods 50 and 50". At their ends remote from the arm 48, the rods 49, 49' are pivotally connected to beams 51, 51' attached respectively to the pistons 40,40. Similarly, the rods 50, 50' are affixed to beams 52, 52' which are likewise affixed respectively, to the pistons 40 40', so that as the arms 48, 48' move in synchronization about their central shaft pivots 53, 53, the pistons 40 and 40" reciprocate accordingly counter to each other within the cylinder 1 I. As will be more completely described with reference to FIGS. 11-16, within each piston 40, 40 is disposed a smaller tubular body 75, concentric and integral, through spokes 87, 87' with the pistons 40, 40', and adapted to receive and guide a stem 78, 78 attached to the valve head 43, 43' in this embodiment. Inthis'embodiment, the port 42 is the intake port and the port 42' is the exhaust port. The pistons 40, 40' are lubricated with suitable liquid oil lubricant at an annulus 59, 59' which is sealed by rings on the pistons 40, 40' and the cylinder 11; and it can be seen that the path of heated exhaust gas prevents substantialcontact thereof with the lubricant, thus avoiding substantial cracking or degradation of the latter.

In the operation of this engine 38, air or an air-fuel mixture is fed through the piston 40 and-its port 42 into a central space 83. When the pistons approach their mid-inward stroke position the valves 43 and 43 are closed and the trapped gas is compressed as the pistons 40 and 40' move further toward each other. At the closesttogether position of the heads 41 and 41', both of the valves 43 and 43' are still seated in their respective ports 42 and 42, and'the compressed gas can be combusted by conventional fuel injection (not shown) or conventional spark ignition (not shown) to generate heat and gaseous products of combustion, forcing the pistons 40 and 40' to move apart, the valves 43 and 43 remaining closed until the pistons 40 and 40' approach their furthest apart position. Then the port 42' is open to withdraw the gaseous products of combustion, which flow outward through the piston 40' and are removed; and the port 42 opens to admit a fresh charge which scavenges the exhaust gas remaining in the space 83. The opening of these valves 43 and 43' will be further described later herein.

As the pistons 40 and 40 recede from each other, the beams 51 and 51' attached thereto, respectively, are forced away from each other and, being connected to the arms 48 and 48' by way of the rods 49, 49', 50, 50, force the arms 48, 48' to assume a position parallel to the axis of cylinder 11 at the farthest-apart position of the heads 41 and 41'. At this time, the ports 42 and 42' are fully open. The pistons 40 and 40' then begin to approach each other again, actuated by the flywheel (not shown).

As the pistons 40 and 40 move apart as described above, and extend the arms 48 and 48, the gears 44 and 47 are actuated, and these in turn actuate the gears 45 and 46 which actuate, respectively, oscillating power take-off shafts 85, 86. When the arms 48 and 48 and the rods 49, 49' and 50, 50' are in their extended position the oscillating flywheel is rotating at its max-' vantageous embodiment the gears are, or the gear train is, adjusted so that the flywheel, which is an oscillating flywheel, oscillates at a higher frequency than that of the rocker arms 48 and 49, preferably several times that of the latter.

FIG. 2 is a schematic plan view of the opposed-piston crank-and-rod engine shown in FIG. 3, FIG. 3 being taken on line 33 of FIG. 2, such the engine comprising engine housing 39 the, common cylinder 11, opposed pistons 54, 54', gears 55, 56,57, 58 and 55', 56, 57' and 58'; and rods 71, 71 and 73, 73', pivotally attached to, respectively, beams 72 and 72 at one end of each such rod and to cranks 67, 68, 67' and 68, respectively, at the other end of each such rod. In an exhaust line 88 from the piston 54 are disposed turbochargers 89 and 90. The crank 67 and the gear are fixed to a shaft 67a. The crank 68 and the gear58 are to the shafts 56a and 57'0. respectively; and such shafts have their bearings on the engine housing 39, and each shaft can be used to transmit power.

FIGS. 4 through 9 represent an opposed .piston cngine and show particularly a means of opening and closing a valve in the head of the piston and the relative positions of the parts at successive stages of the operation. The valve control will be described with respect to one piston, both pistons and accessories operating in like manner and having like parts.

FIG. 4 shows the engine 95 comprising a common cylinder 96 and pistons 97 and 97' having heads 98 and 98', respectively. The piston head 98 is provided with a port 99v disposed centrally thereof to accommodate valve head 100. Disposed centrally with the piston 97 and spaced from its inner wall is a second cylinder 101 having a the head 102 spaced from head 98 to provide passage for incoming gases. A valve stem 103 extends axially of the second cylinder 101 through a suitable aperture in the head 102 and sealed thereto, and at the end opposite to the valve head 100, the valve stem 103 is connected or affixed to a second piston 104 within the cylinder 101 in sliding relationship therewith. The second piston 104 is connected by a plurality of spaced toggle joints 105, suitably three such joints, to another or third piston 106 within the cylinder 101 and facing the base thereof, so that the pistons 104 and 106 can be drawn toward each other in the retracting valve head to its seated position in the port 99. The heads of the pistons 104 and 106 are spaced from the head 102 and a base 107 of the cylinder 101 by pneumatic recoil chambers or springs, or, if desired, by mechanical springs (not shown).

The toggles are pinned at 108 to the piston 104, and at their other end the toggles 105 are pinned at 109 to a bearing structure 110 which is rigidly secured to the inside of the cylinder 101. Links 111 of the toggles 105 have levers 112 rigidly affixed to them so that they rock together. The free ends of the levers 112 are pinned at their free ends 113 to the links 114. The other ends of the links 114 are pinned to the piston 106 at pins 115. A tube or hollow piston rod 116 is secured to the head of the piston 106. The rod 116 extends from the second cylinder 101 through a suitable aperture in the end 107, and a fourth piston 117 reciprocates inside ofthe hollow rod 116. A spring 118 exerts a force on the fourth piston 117; when the spring 118 force is greater than the force of the gas against the end of the fourth piston 117, it forces the fourth piston 117 to a position where a snap latch 119 locks it to an inertia mass 120. At least two rocker arms 121 are pivoted to the mass 120 at a pin 122. One end of the rocker arm 121 is pinned to a link 123 and the other end of the link 123 is pinned to the piston rod 116 to secure the mass 120 to the rod 1.16 when the snap latch fixed to a shaft 680. The gear 56 is keyed to a shaft 56a,

and the gear 57 is keyed to a shaft 57a. The shaft 670. 56a, 57a and 680 have their bearings on the engine housing 39, and each can be used to transmit power. In like manner, the crank 67 and the gear 55 are fixed to the shaft 6711, and the crank 68' and the gear 58 are fixed to the shaft 68'a; the gears 56' and 57' are keyed 119 has locked the fourth piston 117 to the mass 120. At the same time, the free end of the rocker arrn 121 has a roller 124 which has its bearing on it. On a lock ring 125 on the piston 117 The spring 118 bears on the lock ring 125 at one end and against the mass 120 at its other end, such spring 118 holding the parts in locked position until such spring force is overcome. The fourth piston 117 reciprocates in the rod 116, the head of this piston 117 coming into fluid contact through arc holes 149 with high pressure fluid in a recoil chamber 146.

The snap latch means 119 on the mass 120 holds the locking ring 125 in its locked position, and a cam means 137 releases the snap latch 119 (see FIG. 6) when the engine piston 97 approaches its midstroke, moving from the crank end to the head end, whereby the high-pressure fluid in a chamber 147 produced by the recoil stopping of the mass 120 acts through the arc holes 149 on the fourth piston 117 to overcome the spring means 118, forcing it free of the roller 124 whereupon the rocker arm 121 rotates, and the highpressure fluids in the chambers 146 and 147 act on the valve piston 104 and the third piston 106, rapidly closing the valve 100, as the mass 120 moves with the engine piston 97. The fluid force on the fourth piston 117 and the inertia force exerted on the lock ring 125 and on the fourth piston 117 are less than the force of the spring 118 as the engine piston 97 moves from its head end to its crank end, because the valve mechanism is then in its closed position and therefore the pneumatic pressure in the recoil chamber 146 is low, so that the lock ring 125 holds the rocker arm 121 in its position of FIGS. 14, 11, and 12; thus the link 123 etc. holds the mass 120 and the piston 106 together.

It is also to be noted that the third piston 106 moves to reduce pressure in the recoil chamber 146 when the valve 100 closes, so that the inertial force will act on the mass 120 to move the mass 120 to a position where it is fastened to a valve and recoil mechanism by means of the rocker arm 121 having its roller 124 bear on the ring 125, so that the rocker arm 121 and the link 123 hold the mass 120 and the piston 106 together.

The inertia mass 120 has at least two first toggle links 126 pinned to its outboard side and having their bearing on the mass 120 at 127. The other end of the toggle joint 126 may be pinned at 128 tothe outboard end of the piston 97. When the toggle joint 126 is in its extended position, the mass 120 will be connected thereby to the piston 97 and. forced to move with it. A roller 129 has its bearing on the center joint or centrally of the toggle 126. A first cam race 130 for each roller 129 may be secured to an engine housing.142. When the pistons 97, 97' are near their crank end their furthest-apart position the cam race 130 acts on the roller 129 to move the toggle 126 away from its extended position. At other positions, than the crank end, the cam race 130 canbe positioned so that the toggle 126 will be free to move into its extended position.

, To lock the inertial mass 120 to the valve mechanism in opened position when fluid or gas pressure in the recoil chamber 146 is high, there is at least one toggle joint 148 and associated piston arrangement as shown in FIGS. 4 to 9 as described below. Thetoggle joint 148 comprises at least two link members 131, one of which is pivotally connected to the inertial mass 120 at 132 119 may be secured to the engine housing 142. When the engine piston 97 is in its midstroke to its head-end position, the cam race 137 unlatches the snap latch 119 (see FIG. 13).

An annular passage 138 is provided between the inside of the engine piston 97 and the outside of the second cylinder 101 for the passage of intake or exhaust gases therethrough. Ports 139 may be provided in the engine piston 97 to connect the engine housing interior 140 with the annular passage 138.

The engine pistons 97, 97 may be synchronized by means of the semi-free piston mechanism illustrated by FIG. 1 or by the crank-and-rod mechanism illustrated by FIGS. 2 and 3. FIGS. 4 to 9 show the crank-and-rod mechanism, in which a sliding bearing block 141 may be used for each engine connecting rod.

Description of the operation of the engine design shown in FIGS. 4-9

As shown by FIG. 4,'the opposed pistons 97, 97' have reached their maximum outward stroke. The cam races 130, 130' have forced the rollers 129, 129' to trip the toggles 126, 126' from their extended position, and

and the other of which is pivotally connected at 133 to the interior wall of the engine piston 97. At the central or common pivot joint of two toggle links 131 there is pivotally connected a rod or link member 134 which at its other end is pivotally connected to a fifth piston 135 disposed within a cylinder 136, which in turn is in open the inertia forces of the moving mass 120, 120' act through the linkages 121, 123, 116, 106,114, 113, 112, 105, 104, 103, 100, etc. to force the valves 100, open; the latches 119, 119 hold the fourth piston'117, 117' against the pressure force on them and the lock rings 125, 125 bear against the rollers 124, 124' to prevent the rocker arms 122, 122' from rotating. The exhaust valve 100' opens slightly before the intake valve 100, so that the hot exhaust gases can start to blow out of the cylinder 96 before a fresh charge is introduced into the cylinder 96. The inertia forces from on large masses 120, act the pistons 104, 106 to move them to compress air at their respective ends 102, 107 of the cylinder 101, and the fluid pressure in the cylinder end 107 acts in the cylinder 136 on the piston 135 to hold the toggles 1-31, 131 in their near extended position. Thus the toggles 131, 131' will keep the massesl20, 120' and valve linkage mechanism in their open position as shown by FIGS. 4 and 5 until the pressureforce on the pistons 135, 135' is reduced. A stop (not shown) keeps the toggles 131, '131' from reaching their dead center position. I

In FIG. 5 the piston 97 is near its mid-inward stroke position. The central cam 137 is about to release the first-or snap latch 119, so that the compressed fluid in the recoil chamber 146 flows through the arc openings 149 and acts to overpower the spring 1 l8 and to force the piston 117 outwardly and move the lock ring or second latch means clear of the roller 124, so that the rocker arm 121 will rotate (see FIG. 6), whereby the recoil pressure spring energy in the ends 102 and 107 of the cylinder 101 will act on their respective pistons 104 and 106 to force the intake valve 100 closed against the port 99.

In FIG. 6, the piston 97 is just past its mid-inward stroke position. The central cam 137 has released the snap latch 119, and the recoil spring pressure in the chambers 146 and 147 acts on the pistons 104 and 106 to accelerate the closure of the intake valve 100. Since the rocker arm 121 is free to rotate, the recoil springs will not have toaccelerate the large mass 120, and these large recoil pressure forces can act only on the masses of the parts 123, 116,106, 114, 113, 112,111, 105, 108, 104, 103, and 100 which is, even in total, a small fraction of the mass of the mass 120; thus the valve 100 will be closed rapidly as the engine piston 97 move only a fraction of its stroke inward.

In FIG. 7, the piston 97 is near the end of its inward stroke. The pressure in the end 107 of the cylinder 101 has been reduced, and the pressure on the piston 135 is low; thus the inertia forces acting inwardly on the mass 120 will force the toggle 131 fromits nearly extended position. The inward inertial forces on the large mass 120 will force the rocker arm 121 to rotate, and the toggle 126 will be straightened to its extended position, where as a third latch means it can hold the mass and valve mechanism in their closed positions until the engine piston 97 moves to its outward position, so that the cam 130 will act on roller 129 to force the toggle 126 out of its extended position. The air pressure on the pistons 117 has been reduced, so that the spring 118 and the inward inertia on piston 117 will force them inwardly so that the roller 124 will bear on the lock ring 125, thus keeping the rocker arm 121 from rotating. Also, the snap latch 119 is in a position to keep the piston 117 from moving outward with reference to the engine pistons 97. The high pressures in the engine cylinder 96 act on the valves 100, 100' to keep them closed against their ports 99, 99'. The mechanisms within the piston 97 stay in their relative positions of FIG. 7 at the head end until the engine piston 97 moves to the outward stroke position shown by FIG, 8. I g

In the operation of the engine 95, the cam race 130' (shown in FIG. 4) is so set that it first acts on the roller' 129', then a fraction of the stroke thereafter the cam race 130 acts on the roller 129 (note FIG. 8). Thus the toggles 126- and 126 are forced from their extended positions. The inertia forces on the mass 120' which are outward will act through the linkages 12 1, 123', 116', 106', 114',113',112',105,l04, 103',100'to force are also outward, will act through linkages 121, 123,

I16, 106, 114, 1 13, 112, 105, 104, 1 03, 100, forcing the intake valve 100 open so that a fresh charge of supercharged airwill flow through the ports 139, annulus 138 and intake port 99 into the engine cylinder'96. The engine pistons-97, 97 thus return to their FIG. 4 position and the cycle has been completed and will be repeated.

FIGS. 10 to 14 show an another opposed piston engine. The opposed pistons 301 and 301' may be synchronized by the cranks 67, 68, 67', 68' and the connecting rods 71, 71' (not shown 'here, see FIG. 5), beams 72 and 72 (not shown here; see FIG. 5) and tie rods 315 and 315. Both pistons 301 and 301 are constructed and disposed in the same manner and operate in the same way. Therefore, only one will be completely shown and described, with part only of the opposed piston and accessories, for brevity.

The opposed pistons 301,301 reciprocate in a common cylinder 300. Each of the pistons 301, 301' has at least one poppet valve 303,303 which seats in a valve port 302, 302', respectively, in the piston head. The pistons 301, 301 have casings 304, 304', respectively, secured to them.

A stem 305 of valve 303 reciprocates in its casing 304 when actuated by cam means 311. Helical spring means 307 forces valve the 303 to seat in its valve port 302 when the cam 311 does not act on the valve stem 305 to open the valve 303. The spring bears on the easing 304 at one end and on a lock ring 306 which is secured to the valve 305 stem at its other end or the tip of the stem 305, ie the end remote from the valve 303. The lock ring 306 reciprocates on a lubricated bearing surface inside of the casing 304. The casing 304 reciprocates freely on a lubricated bearing surface inside of the housing 314 for a camshaft 310. The housing 314 is secured to the housing for the cylinder 300. The camshaft 310 may be driven by actuating crankshafts (not shown) at twice the rotating speed of the crankshafts. When the piston 301 is at its furthest outward position, at its crank end, the cam 311 is rotated by the camshaft 310 to contact a valve stem end 309 and to open the valve 303. When the piston 301 moves inwardly from its furthest-outward position (furthest-apart positions of the two pistons 301 and 301') to its midstroke position, the cam 311 turns to hold the valve 303 open so that a fresh charge of air will flow into the cylinder 300through the intake port 302 and the burnt gases will exhaust from the cylinder 300 through the port 302. When the pistons 301 and 301' move from their midstroke position to their closest together or farthest-inward position or head position, and then apart to the midstroke position in operation,

- the cam 311 may make one 360 revolution freely without any valve forces acting on it, as the valve 303. moves with the piston 301 and makes a clearance gap between the cam 311 and the valve tip 309 during this part ofthecycle. During the expansion stroke of the piston 301 as it moves toward the crank end, the valve 303 stays seated against its port 302 by means of gas pressure in ,the cylinder 300 and by the spring 307 acting on the valve 303. As the pistons 301 and 301' approach their crank end or furthest apart position, the controlling cam (not shown corresponding to the cam 311, is synchronized to rotate and, to open the exhaust port 302 first, so that hot expanded high pressure burnt gases will start exhausting through the port 302'.

The camshaft 310 turns a few degrees, then the cam 301' are closest together. Oil lubricating means 313 can be used to lubricate the surface between the reciprocating piston 301 and the cylinder 300.

Operation of the Valve Mechanism Shown in FIGS. 10 to 14.

As shown in FIG. 10, the engine pistons 301 and 301' are approaching their maximum outward position. The

controlling cam (not shown) rotates to open the exhaust port 302' so that the hot high pressure gases which have been expanded in the cylinder 300 will flow through the port 302' into a passage 316'. The

camshaft 310 turns a few degrees and the cam 311 turns to act on the valve stem tip 309 to open the valve 303, so that a fresh charge of air willflow through the intake port 302 and help to scavenge the cylinder 300 Where the pistons 301 and 301' are furthest apart, the cam 31] continues to turn so that the valve 303, and correspondingly the valve 303, will be opened completely by the time each piston 301,301 reaches the position shown in FIG. 11. A supercharger (not shown) forces a fresh charge of air to flow through a passage 316 and the port 302 into the cylinder 300', and the burnt gases flow out of the cylinder 300 through the port 302' into the passage 316. The respective cams continue to rotate and open the valves 303 to 303 as the pistons 301 and 301' move together to their midstroke position, illustrated in FIG. 12.

After reaching their midstroke position, the pistons 301 and 301 move closer together, so that the ports 302 and 302' seat against their respective valves 303 and 303 and the valve stem tips 309 and 309' are then moved away from the actuating cams 311 and 311. The air trapped in the cylinder 300 is compressed and the high pressure air holds the valves 303 and 303' closed against their ports 302 and 302 as the pistons 30] and 301' move together to their closest together position shown by FIG. 13, at whichpoint fuel is exploded in the cylinder 300. The actuating camshafts 310 and 310 are timed to rotate at twice the speed of the crankshafts 67, 67', 68, 68', and thus, when the pistons 301 and 30] move from'their midstroke position to their closest together position and back to their furthest apart position, the actuating cams 310 and 310' may make more than a complete revolution without contacting the respective valve stems 305, 305. In a preferred operation, each cam 310, 310

rotates at twice the speed of the piston 301, 301

frequency, making two revolutions during one piston cycle.

The hot compressed gases in the cylinder300 expand and do work on the' pistons 301 and 301', forcing them apart to their furthest-apart position, illustrated by FIG. 10. The actuating cam 311 rotates to bear on the valve stem end 309' and to open the exhaust port 302', so that the hot high pressure gases which have been expanded in the cylinder 300 will flow through the port 302' into the passage 316'. The pistons 301- and 301' move toward their crank end, and the crankshafts turn a few degrees, rotating the cam 311 so that it bears on the valve stem 305 to open the valve 303, whereby a fresh charge of air will flow through the intake port 302 and help to scavenge the cylinder 300. The cycle is thus completed and will repeat itself.

The above specific description and the drawings have been given for purposes of illustration and variations and modifications can be made therein without departing from the spirit and scope of the appended claims. Where an element is described as pinned to another element, it will be understood that such element is pivotally attached thereto.

Having now described the invention, 1 claim:

1. In an opposed-piston two-cycle engine including a first piston, a second piston, a cylinder having first and second ends, each said piston having a sliding surface engaging said cylinder, said pistons having facing heads and opposite ends distant from said heads, and means to introduce gas and air into said cylinder, said'pistons being adapted to reciprocate toward and apart from each other in said cylinder, said pistons being lubricated with liquid lubricant, the improvement comprising:

a. said first piston being hollow and having an intake port in its said head,

means for introducing intake air into said opposite end of said first piston and through said first piston and-through said intake port thereby preventing direct impact with the sliding surface of said first piston,

c. said second piston being hollow and having an exhaust port in its said head,

[means for exhausting gases from said exhaust port through said second piston and out through said opposite end of said second piston, thereby preventing direct impact with the sliding surface of said second piston,

e. an intake valve for said intake port,

f. an exhaust valve for said exhaust port, and

g. valve actuating means tooperate said valves to exhaust, scavenge, and charge intake fluids all unidirectionally through said cylinder ends, said valve actuating means including means for causing said intake and exhaust valves to ,be simultaneously unseated from their ports during certain times, and

sealing means between said pistons and, said cylinder to restrict the flow of lubricant substantially to said sliding surfaces and for minimizing contact between said lubricant and said air and gases, to reduce consumption of said lubricant.

. An engine as in claim! having means to open said exhaust valve as said pistons nearly approach their farthest apart position to cause gas to exhaust through said piston,

. means to open said intake valve after said exhaust valve openswhereby to draw a fresh charge of air through said first-mentioned piston into said cylinder to give unidirectional flow through said cylinder,

open from their farthest apart position to about their mid-inward'stroke position whereby said engine is exhausted, scavenged and charged with a fresh charge of air,

. means to'close said intake and exhaust valves when said pistons approach their inward midstroke position whereby air trapped in'said cylinder is compressed as said pistons move together from their mid-stroke to their closest together position, g f

. means to introduce fuel into said air in said cylinder,

f. means to explode fuel in said air when said pistons are closest together to form gaseous products of combustion, and

. means to hold said exhaust-and intake valves closed as said pistons move outward from said means to hold said exhaust and said intake valvesl3 closest together position to said farthest apart posi tion whereby said gaseous products of combustion do useful work on said pistons to provide power during said move outward of said piston. 3. An engine as in claim 2 wherein: a. said intake and exhaustvalves are actuated by inertia means in said pistons, and v latch means tohold said valves closed from head end to mean crank end,

c. cam race means to release said latch means at said crank end so said inertia means will force said valves open. An engine as in claim 1 wherein:

a. said intake and exhaust valves are actuated by inertia means in said pistons, and

b. latch means to hold said valves closed from head end to mean crank end,

c. cam race means to release said latch means at said crank end so said inertia means will force said valves open.

5. In a two-cycle piston engine including a cylinder and a piston adapted to reciprocate within said cylinder, the improvement wherein said piston has a head at one end, an opposite end, and a cylindrical slid ing surface between said ends, said piston head having exhaust port means therein, and exhaust ducting means in communication with said port and leading out axially through said opposite end of said piston, so that the exhaust ducting does not impinge upon said sliding sur' face.

6. In an engine .having a crankcase and a cylinder with a head' end and a crank end, the combination therewith of a. a piston having a cylindrical side wall, a head facing said cylinder head end and having a distal end,

b. exhaust port means comprising an opening in said piston head,

c. a valve to open and close said port when the piston is at said crank end,

d. exhaust ducting connected through said piston from said exhaust port to and through said distal end rather than through said side wall, conducting the hot exhaust gases from said exhaust port and through ducting in a path avoiding direct impact with the oil-lubricated surface between the engine piston and the engine cylinder in which the piston reciprocates, to minimize lubricating oil loss and heat cracking of lubricating oil by the hot exhaust gases, said exhaust ducting going through said engine crankcase into the engine exhaust system.

7. The engine of claim 6 wherein said exhaust valve is actuated by an inertia operated valve mechanism.

87 An opposed-piston two-cycle engine having a cylinder having first and second ends and a central portion therebetween'and first and second pistons in said cylinder reciprocating toward and away from each other and having facing heads, the head of said first piston having an inlet valve, and the head of said second piston having an exhaust valve, said valves acting in an axial direction with respect to said cylinder, an

intake duct through said first piston leading out said first end and an exhaust duct through said second piston leading out said second end, including therewith a system for unidirectionally charging, exhausting, and

scavenging gas between said firstand second ends,

comprising:

means for opening said exhaust valve when said pistons closely approach their furthestapart positions, so that the gas between said heads enters said second piston for flow out through said exhaust duct,

means for opening said intake valve after said ex haust valve has opened and while it is still open and for drawing a fresh charge of air through said intake duct and imparting a unidirectional flow through said cylinder, means for holding said exhaust and intake valves open while said pistons move from their furthestapart positions to approximately a mid-stroke position, thereby exhausting and scavenging said cylinder and charging it with a fresh charge of air,

means for then closing said exhaust and intake valves at approximately said mid-stroke position, thereby trapping the fresh charge of air in said central portion of said cylinder between said heads, so that the trapped air is compressed as the pistons move toward each other from their mid-stroke position to their closest-together position,

means for introducing fuel into said central portion of said-cylinder,

means for exploding said fuel in said trapped and compressed air when said pistons are in their closest-together position, and

means for holding 'said exhaust and intake valves closed'while said pistons 'move apart from each other and the combustion products do useful work on said pistons.

9. The engine of claim 8 wherein said means for opening, said means for holding, and said means for closing said intake and exhaust valves comprises first latch means, I

said valve being held seated against said port by gas pressure in said engine and by said first latch means as said piston moves from the head end to the crank end of said cylinder during operation of said engine,

first cam means to release said first latch as said piston approaches said crank end, whereby an inertial mass actuated by said piston actuates said valve to open said valve,

a recoil spring to store inertial energy of said valve and said inertial mass, second latch means to hold. said valve and said inertial mass at maximum open position of said valve, .whereby said recoil spring is stored,

second cam means to release said second latch means as said piston approaches its mid-stroke position,

said recoil spring acting todrive said valve closed against itsport and hold said valve closed from said mid-stroke positionto head end position of said piston, and

means to move said first latch means to lock said valve closed.

10. The engine of claim 8 wherein said means for opening, said means for holding, and said mean-s for closing said intake and said exhaust valves comprises first latch means,

said valve being held seated against said port by gas pressure in said engine andby said first latch means as said piston moves from the head end to the crank end of said cylinder during operation of said engine,

first cam means to release said first latch means as said piston approaches said crank end, whereby an inertial mass actuated by said piston actuates said valve to open said valve,

a recoil spring to store the inertial energy of said valve and said inertial mass,

second latch means to lock said valve and said recoil spring to said inertial mass,

third latch means on said inertial mass to lock said inertial mass and valve in maximum open position in combination with recoil spring pressure,

second cam means to release said recoil-spring and valve from said inertial mass as said piston approaches its mid-stroke position,

said recoil spring acting to close said valve rapidly whereby it is closed from about mid-stroke posi tion to head end position, and

means to release said recoil spring pressure whereby to release said third latch means to enable said inertial mass to return to a position where said second latch will engage said valve and recoil spring.

11. The engine of claim 10 wherein:

a. said valve is a poppet valve adaptedto be held closed by high pressure gases insaid engine while said piston moves from said head end to said crank end,

b. said valve is provided with a valve stem having a valve piston at its end remote from said valve,

0. a second cylinder having a head :is concentrically disposed with said first-mentioned piston and is provided with an aperture in said head, i

d. said valve stemrreciprocates in said aperture and said valve piston reciprocates within said second cylinder,

e. said second cylinder having a recoil air chamber, its cylinder between its head and said valve piston to store compressed air to-drive said valve closed.

12. The engine according to claim 11 wherein said mechanism to open said valve includes a means for actuating motion of said valve comprising:

a. a plurality of spaced toggle joints each pivotally attached to said valve piston at one end and affixed to said second cylinder at its other end,

. a lever rigidly affixed at said other end of each said toggle joint,

c; a third piston also disposed within said second cylinder,

said third piston,

e. said third piston and saidsecond cylinder co-acting to form a second pneumatic recoil chamber for storing compressed gas to drive said valve closed,

f. a hollow-rod extending outwardly from said third piston and affixed thereto, the interior of said rod a link member affixed to each of said levers and to being in open communication with said second teriorly of said second cylinder and pivotally connected to said-hollow tube by said second latch means.

13. The engine according to claim 10 wherein said first latch means comprises:

a. an extended toggle joint with a link pivotally affixed to said first-mentioned pistonat one end and to a further link at its other end,

b. said further link being pivotally attached to said inertial mass,

c. both said links being in extended position when said valve mechanism locks said valve closed,

d. a roller disposed centrally of said toggle joint,

e. said first cam means being adapted to exert a force normal to said roller when said toggle joint is in ex-- tended position to force said links torotate in co action with inertia forces of said inertial mass whereby to open said valve and to compress air in said recoil chambers.

14. The engine according to claim 10 wherein said second latch means comprises:

a. at least one rocker arm pivoted on said inertial mass,

b. a link member pivotally connected to said rocker arm and to said hollow rod,

c. a roller disposed on said rocker arm,

d. a lock ring disposed around said hollow rod and adjacent said inertial mass,

e. said roller being adapted to bear on said lock ring and to maintain said rocker arm and link member in contracted position to latch said mass to said valve mechanism,

f. a spiral spring abutting said lock ring to maintain said ring in locking position,

g, a fourth piston reciprocating in said hollow rod and in fluid pressure contact with a second recoil chamber h. a snap latch disposed around said second cam race to lock said second latch means in locked position and adapted to be released by said second cam means when said first-mentioned or engine piston approaches its mid-strokefrom said crank end toward said head end.

15. The engine of claim 14 wherein the forces exerted on said fourth piston by said fluid pressure and said inertia mass and on said lock ring by said inertia mass are less than that of said first spring as said piston moves from head end to crank end with said valve in closed position, and said lock ring holds said second latch closed. V

16. The engine according to claim 14 wherein said inertial mass is actuated to open said valve by a third latch means comprising:

a. a toggle joint pivotally connected to said inertial 7 mass and to a wall of said engine piston,

b. said toggle joint having a central pivot joint, c. a linkmember pivotally attached to said toggle at said central pivot joint,

' d. a fifth cylinder affixed to said wall of said engine piston,

. a second recoil chamber,

. said fifth cylinder being in open communication with said chamber, and

g. a piston slidably disposed in said fifth cylinder and pivotally connected to said link member.

17. The engine accordingto claim 16 comprising at least two valve mechanisms, at least two first latch means, at least two second latch means, and at least two third latch means so arranged as to be in dynamic balance upon operation of the valves.

18. The engine according to claim 16 wherein said valve mechanismand said first, second, and third latch means are arranged to be in dynamic balance upon operation of said valve.

19. A two-cycle piston engine having at least one cylinder having a head end and a crank end, at least one piston having a piston head and adapted to reciprocate in said cylinder, a housing for said cylinder, at least one valve means disposed in said piston head and having a valve stem, and spring means disposed within said piston and urging said valve means toward a closed position, the improvement comprising in combination,

cam means at the crank end of said cylinder bearing on said housing and adapted to rotate and to bear against said valve means to open the same only when said piston is closely approaching said crank end and and to increase the opening of said valve means as said piston moves through a predetermined distance away from said crank end said cam, at a predetermined position of the travel of said piston, causing said valve to seat in its closed position, the compressed gas within said cylinder at said piston head then cooperating with said' spring means to hold said valve closed. 20. The engine of claim 8 having sealing means for each piston adjacent opposite ends thereof of their sliding surfaces which engage the cylinder, said sealing means and sliding surfaces being confined at all times within said cylinder, serving to retain lubricant between said sliding surfaces and said cylinder, said sealingmeans cooperating with said intake duct, intake valve, exhaust valve, and exhaust duct to'cause unidirectional flow of gas through said cylinder without directly flow ing on said sliding surfaces or the lubricant thereon.

21. The engine of claim 8 wherein the means for opening, holding, and closing the intake and exhaust valves comprises:

a valve stem for each said valve,

housing means at each end of said cylinder,

cam means at each end of said cylinder bearing on said housing means and bearing against. a said valve stem, cam actuating means for rotating said cam means so that each one opens its said valve means at a predetermined time in the engine cycle, when the pistons are moving toward the crank end of the cylinder and closely approach thereto, and spring means for each said valve, insidesaid piston and urging said valve toward a normally closed position. a I I 22. In an engine having a'crankcase, a cylinder having a head end and a crank end, and a piston having a head facing said cylinder head end, an opposite end, and a sliding surface engaging said cylinder. and lubricated with liquid lubricant, the improvement com prising: I v a. said piston being hollow and having-an exhaust headend. 7

cylinder to rest rict the flow of lubricantsubstgmtially to said sliding surfaces and for minimizmg contact between said lubricant and the exhaust gases, to reduce consumption of said lubricant.

23. An engine as'in claim 19 having two opposed pistons in each said cylinder, one of said pistons having a head and an intake port and valve therein, and the other of said pistons having a head and an outlet port and valve therein.

24. An engine as in claim 19 wherein each said cam is adapted to bear directly on said valve stem to actuate said valve means.

25. An engine as in claim 19 wherein said cam is adapted to rotate at twice the speed of the frequency of said piston.

26. An engine as in claim 19 wherein said predetermined position is about midstroke of said piston toward its head end.

27. In an engine as in claim 19, a mechanism for operating said valve comprising in combination:

a. said valve means seating in a port in said piston head, g spring means disposed within said piston and bear ing on said stem and piston and adapted to help hold said valve closed against said port,

c. cam means adapted to rotate and to intermittently bear upon said stem to open said valve when said piston approaches its crank end and to increase opening of said valve as said piston moves a predetermined distance away from said crank end,

at a predetermined point in its travel, and e. compressed gas disposed within said cylinder at said piston head and being adapted to co-act with said spring to hold said valve closed. 28. A mechanism as in claim 27 wherein two opposed pistons are disposed within said cylinder, one said piston head having an intake port and valve therein, and the other saidpiston head having an outlet port and valve therein.

29. Mechanism as in-claim 27 wherein said predetermined point is about midstroke of said piston toward its 'Ji t t t i said piston being adapted to seat against said port 

1. In an opposed-piston two-cycle engine including a first piston, a second piston, a cylinder having first and second ends, each said piston having a sliding surface engaging said cylinder, said pistons having facing heads and opposite ends distant from said heads, and means to introduce gas and air into said cylinder, said pistons being adapted to reciprocate toward and apart from each other in said cylinder, said pistons being lubricated with liquid lubricant, the improvement comprising: a. said first piston being hollow and having an intake port in its said head, b. means for introducing intake air into said opposite end of said first piston and through said first piston and through said intake port thereby preventing direct impact with the sliding surface of said first piston, c. said second piston being hollow and having an exhaust port in its said head, d. means for exhausting gases from said exhaust port through said second piston and out through said opposite end of said second piston, thereby preventing direct imPact with the sliding surface of said second piston, e. an intake valve for said intake port, f. an exhaust valve for said exhaust port, and g. valve actuating means to operate said valves to exhaust, scavenge, and charge intake fluids all unidirectionally through said cylinder ends, said valve actuating means including means for causing said intake and exhaust valves to be simultaneously unseated from their ports during certain times, and h. sealing means between said pistons and said cylinder to restrict the flow of lubricant substantially to said sliding surfaces and for minimizing contact between said lubricant and said air and gases, to reduce consumption of said lubricant.
 2. An engine as in claim 1 having a. means to open said exhaust valve as said pistons nearly approach their farthest apart position to cause gas to exhaust through said piston, b. means to open said intake valve after said exhaust valve opens whereby to draw a fresh charge of air through said first-mentioned piston into said cylinder to give unidirectional flow through said cylinder, c. means to hold said exhaust and said intake valves open from their farthest apart position to about their mid-inward stroke position whereby said engine is exhausted, scavenged and charged with a fresh charge of air, d. means to close said intake and exhaust valves when said pistons approach their inward mid-stroke position whereby air trapped in said cylinder is compressed as said pistons move together from their mid-stroke to their closest together position, e. means to introduce fuel into said air in said cylinder, f. means to explode fuel in said air when said pistons are closest together to form gaseous products of combustion, and g. means to hold said exhaust and intake valves closed as said pistons move outward from said closest together position to said farthest apart position whereby said gaseous products of combustion do useful work on said pistons to provide power during said move outward of said piston.
 3. An engine as in claim 2 wherein: a. said intake and exhaust valves are actuated by inertia means in said pistons, and b. latch means to hold said valves closed from head end to mean crank end, c. cam race means to release said latch means at said crank end so said inertia means will force said valves open.
 4. An engine as in claim 1 wherein: a. said intake and exhaust valves are actuated by inertia means in said pistons, and b. latch means to hold said valves closed from head end to mean crank end, c. cam race means to release said latch means at said crank end so said inertia means will force said valves open.
 5. In a two-cycle piston engine including a cylinder and a piston adapted to reciprocate within said cylinder, the improvement wherein said piston has a head at one end, an opposite end, and a cylindrical sliding surface between said ends, said piston head having exhaust port means therein, and exhaust ducting means in communication with said port and leading out axially through said opposite end of said piston, so that the exhaust ducting does not impinge upon said sliding surface.
 6. In an engine having a crankcase and a cylinder with a head end and a crank end, the combination therewith of a. a piston having a cylindrical side wall, a head facing said cylinder head end and having a distal end, b. exhaust port means comprising an opening in said piston head, c. a valve to open and close said port when the piston is at said crank end, d. exhaust ducting connected through said piston from said exhaust port to and through said distal end rather than through said side wall, conducting the hot exhaust gases from said exhaust port and through ducting in a path avoiding direct impact with the oil-lubricated surface between the engine piston and the engine cylinder in which the piston reciprocates, to minimize lubricating oil loss and heat cracking of lubricating oil by the hot eXhaust gases, said exhaust ducting going through said engine crankcase into the engine exhaust system.
 7. The engine of claim 6 wherein said exhaust valve is actuated by an inertia operated valve mechanism.
 8. An opposed-piston two-cycle engine having a cylinder having first and second ends and a central portion therebetween and first and second pistons in said cylinder reciprocating toward and away from each other and having facing heads, the head of said first piston having an inlet valve, and the head of said second piston having an exhaust valve, said valves acting in an axial direction with respect to said cylinder, an intake duct through said first piston leading out said first end and an exhaust duct through said second piston leading out said second end, including therewith a system for unidirectionally charging, exhausting, and scavenging gas between said first and second ends, comprising: means for opening said exhaust valve when said pistons closely approach their furthest-apart positions, so that the gas between said heads enters said second piston for flow out through said exhaust duct, means for opening said intake valve after said exhaust valve has opened and while it is still open and for drawing a fresh charge of air through said intake duct and imparting a unidirectional flow through said cylinder, means for holding said exhaust and intake valves open while said pistons move from their furthest-apart positions to approximately a mid-stroke position, thereby exhausting and scavenging said cylinder and charging it with a fresh charge of air, means for then closing said exhaust and intake valves at approximately said mid-stroke position, thereby trapping the fresh charge of air in said central portion of said cylinder between said heads, so that the trapped air is compressed as the pistons move toward each other from their mid-stroke position to their closest-together position, means for introducing fuel into said central portion of said cylinder, means for exploding said fuel in said trapped and compressed air when said pistons are in their closest-together position, and means for holding said exhaust and intake valves closed while said pistons move apart from each other and the combustion products do useful work on said pistons.
 9. The engine of claim 8 wherein said means for opening, said means for holding, and said means for closing said intake and exhaust valves comprises first latch means, said valve being held seated against said port by gas pressure in said engine and by said first latch means as said piston moves from the head end to the crank end of said cylinder during operation of said engine, first cam means to release said first latch as said piston approaches said crank end, whereby an inertial mass actuated by said piston actuates said valve to open said valve, a recoil spring to store inertial energy of said valve and said inertial mass, second latch means to hold said valve and said inertial mass at maximum open position of said valve, whereby said recoil spring is stored, second cam means to release said second latch means as said piston approaches its mid-stroke position, said recoil spring acting to drive said valve closed against its port and hold said valve closed from said mid-stroke position to head end position of said piston, and means to move said first latch means to lock said valve closed.
 10. The engine of claim 8 wherein said means for opening, said means for holding, and said means for closing said intake and said exhaust valves comprises first latch means, said valve being held seated against said port by gas pressure in said engine and by said first latch means as said piston moves from the head end to the crank end of said cylinder during operation of said engine, first cam means to release said first latch means as said piston approaches said crank end, whereby an inertial mass actuated by said piston actuates said valve to open said valve, a recoil spring to store the inertial energy of said valve and said inertial mass, second latch means to lock said valve and said recoil spring to said inertial mass, third latch means on said inertial mass to lock said inertial mass and valve in maximum open position in combination with recoil spring pressure, second cam means to release said recoil spring and valve from said inertial mass as said piston approaches its mid-stroke position, said recoil spring acting to close said valve rapidly whereby it is closed from about mid-stroke position to head end position, and means to release said recoil spring pressure whereby to release said third latch means to enable said inertial mass to return to a position where said second latch will engage said valve and recoil spring.
 11. The engine of claim 10 wherein: a. said valve is a poppet valve adapted to be held closed by high pressure gases in said engine while said piston moves from said head end to said crank end, b. said valve is provided with a valve stem having a valve piston at its end remote from said valve, c. a second cylinder having a head is concentrically disposed with said first-mentioned piston and is provided with an aperture in said head, d. said valve stem reciprocates in said aperture and said valve piston reciprocates within said second cylinder, e. said second cylinder having a recoil air chamber, its cylinder between its head and said valve piston to store compressed air to drive said valve closed.
 12. The engine according to claim 11 wherein said mechanism to open said valve includes a means for actuating motion of said valve comprising: a. a plurality of spaced toggle joints each pivotally attached to said valve piston at one end and affixed to said second cylinder at its other end, b. a lever rigidly affixed at said other end of each said toggle joint, c. a third piston also disposed within said second cylinder, d. a link member affixed to each of said levers and to said third piston, e. said third piston and said second cylinder co-acting to form a second pneumatic recoil chamber for storing compressed gas to drive said valve closed, f. a hollow rod extending outwardly from said third piston and affixed thereto, the interior of said rod being in open communication with said second chamber, and g. an inertial mass disposed within said first piston exteriorly of said second cylinder and pivotally connected to said hollow tube by said second latch means.
 13. The engine according to claim 10 wherein said first latch means comprises: a. an extended toggle joint with a link pivotally affixed to said first-mentioned piston at one end and to a further link at its other end, b. said further link being pivotally attached to said inertial mass, c. both said links being in extended position when said valve mechanism locks said valve closed, d. a roller disposed centrally of said toggle joint, e. said first cam means being adapted to exert a force normal to said roller when said toggle joint is in extended position to force said links to rotate in co-action with inertia forces of said inertial mass whereby to open said valve and to compress air in said recoil chambers.
 14. The engine according to claim 10 wherein said second latch means comprises: a. at least one rocker arm pivoted on said inertial mass, b. a link member pivotally connected to said rocker arm and to said hollow rod, c. a roller disposed on said rocker arm, d. a lock ring disposed around said hollow rod and adjacent said inertial mass, e. said roller being adapted to bear on said lock ring and to maintain said rocker arm and link member in contracted position to latch said mass to said valve mechanism, f. a spiral spring abutting said lock ring to maintain said ring in locking position, g. a fourth piston reciprocating in said hollow rod and in fluid pressure contaCt with a second recoil chamber h. a snap latch disposed around said second cam race to lock said second latch means in locked position and adapted to be released by said second cam means when said first-mentioned or engine piston approaches its mid-stroke from said crank end toward said head end.
 15. The engine of claim 14 wherein the forces exerted on said fourth piston by said fluid pressure and said inertia mass and on said lock ring by said inertia mass are less than that of said first spring as said piston moves from head end to crank end with said valve in closed position, and said lock ring holds said second latch closed.
 16. The engine according to claim 14 wherein said inertial mass is actuated to open said valve by a third latch means comprising: a. a toggle joint pivotally connected to said inertial mass and to a wall of said engine piston, b. said toggle joint having a central pivot joint, c. a link member pivotally attached to said toggle at said central pivot joint, d. a fifth cylinder affixed to said wall of said engine piston, e. a second recoil chamber, f. said fifth cylinder being in open communication with said chamber, and g. a piston slidably disposed in said fifth cylinder and pivotally connected to said link member.
 17. The engine according to claim 16 comprising at least two valve mechanisms, at least two first latch means, at least two second latch means, and at least two third latch means so arranged as to be in dynamic balance upon operation of the valves.
 18. The engine according to claim 16 wherein said valve mechanism and said first, second, and third latch means are arranged to be in dynamic balance upon operation of said valve.
 19. A two-cycle piston engine having at least one cylinder having a head end and a crank end, at least one piston having a piston head and adapted to reciprocate in said cylinder, a housing for said cylinder, at least one valve means disposed in said piston head and having a valve stem, and spring means disposed within said piston and urging said valve means toward a closed position, the improvement comprising in combination, cam means at the crank end of said cylinder bearing on said housing and adapted to rotate and to bear against said valve means to open the same only when said piston is closely approaching said crank end and and to increase the opening of said valve means as said piston moves through a predetermined distance away from said crank end said cam, at a predetermined position of the travel of said piston, causing said valve to seat in its closed position, the compressed gas within said cylinder at said piston head then cooperating with said spring means to hold said valve closed.
 20. The engine of claim 8 having sealing means for each piston adjacent opposite ends thereof of their sliding surfaces which engage the cylinder, said sealing means and sliding surfaces being confined at all times within said cylinder, serving to retain lubricant between said sliding surfaces and said cylinder, said sealing means cooperating with said intake duct, intake valve, exhaust valve, and exhaust duct to cause unidirectional flow of gas through said cylinder without directly flowing on said sliding surfaces or the lubricant thereon.
 21. The engine of claim 8 wherein the means for opening, holding, and closing the intake and exhaust valves comprises: a valve stem for each said valve, housing means at each end of said cylinder, cam means at each end of said cylinder bearing on said housing means and bearing against a said valve stem, cam actuating means for rotating said cam means so that each one opens its said valve means at a predetermined time in the engine cycle, when the pistons are moving toward the crank end of the cylinder and closely approach thereto, and spring means for each said valve, inside said piston and urging said valve toward a normally closed position.
 22. In an engine having a crankcase, a cylinder hAving a head end and a crank end, and a piston having a head facing said cylinder head end, an opposite end, and a sliding surface engaging said cylinder and lubricated with liquid lubricant, the improvement comprising: a. said piston being hollow and having an exhaust port it its said head, b. means for exhausting gases from said exhaust port through said piston and out through said opposite end and through said crank end of said cylinder at a locus beyond any place engaged by said sliding surface and for thereby guiding said gases via a path having no direct impact with the sliding surface of said piston. c. an exhaust valve for said exhaust port, and d. sealing means between said piston and said cylinder to restrict the flow of lubricant substantially to said sliding surfaces and for minimizing contact between said lubricant and the exhaust gases, to reduce consumption of said lubricant.
 23. An engine as in claim 19 having two opposed pistons in each said cylinder, one of said pistons having a head and an intake port and valve therein, and the other of said pistons having a head and an outlet port and valve therein.
 24. An engine as in claim 19 wherein each said cam is adapted to bear directly on said valve stem to actuate said valve means.
 25. An engine as in claim 19 wherein said cam is adapted to rotate at twice the speed of the frequency of said piston.
 26. An engine as in claim 19 wherein said predetermined position is about midstroke of said piston toward its head end.
 27. In an engine as in claim 19, a mechanism for operating said valve comprising in combination: a. said valve means seating in a port in said piston head, b. spring means disposed within said piston and bearing on said stem and piston and adapted to help hold said valve closed against said port, c. cam means adapted to rotate and to intermittently bear upon said stem to open said valve when said piston approaches its crank end and to increase opening of said valve as said piston moves a predetermined distance away from said crank end, d. said piston being adapted to seat against said port at a predetermined point in its travel, and e. compressed gas disposed within said cylinder at said piston head and being adapted to co-act with said spring to hold said valve closed.
 28. A mechanism as in claim 27 wherein two opposed pistons are disposed within said cylinder, one said piston head having an intake port and valve therein, and the other said piston head having an outlet port and valve therein.
 29. Mechanism as in claim 27 wherein said predetermined point is about midstroke of said piston toward its head end. 